Fiber optic breakout cassettes are merely one form of passive optical interconnect devices commonly used for distributing signals between one or more transmit optical components and one or more receive optical components (often in opposite directions simultaneously).
Other common passive optical interconnect devices are optical multiplexers and demultiplexers, which comprise a flexible optical circuit, for distributing signals between one or more single- or multi-fiber optical connectors on the one hand and one or more single- or multi-fiber optical connectors on the other hand. Other common forms of optical interconnect include simple patch cables and optical splitters.
Flexible optical circuits are passive optical components that comprise one or more (typically multiple) optical fibers imbedded on a flexible substrate, such as a Mylar® or other flexible polymer substrate. Commonly, although not necessarily, one end face of each fiber is disposed adjacent one longitudinal end of the flexible optical circuit substrate and the other end face of each fiber is disposed adjacent the opposite longitudinal end of the flexible optical circuit substrate. The fibers extend past the longitudinal ends of the flexible optical circuit (commonly referred to as pigtails) so that they can be terminated to optical connectors, which can be coupled to fiber optic cables or other fiber optic components through mating optical connectors.
Flexible optical circuits are known, and hence, will not be described in detail. However, they essentially comprise one or more fibers sandwiched between two flexible sheets of material, such as Mylar® or another polymer. An epoxy may be included between the two sheets in order to make them adhere to each other. Alternately, depending on the sheet material and other factors, the two sheets may be heated above their melting point to heat weld them together with the fibers embedded between the two sheets.
FIG. 1, for example, shows a flexible optical circuit 100 that might be used in an optical multiplexer/demultiplexer. This flexible optical circuit 100 commonly is referred to as a shuffle. FIG. 2 shows a complete optical multiplexer/demultiplexer 200 including the shuffle 100 and a housing 102. The top of the housing is removed in FIG. 2 to allow viewing of the internal components of the device 200. This particular optical multiplexer/demultiplexer 200 is intended to distribute signals between a set of eight multi-fiber optical cables 201 on the right side of the figure, each containing eight fibers (not shown), and another set of eight optical cables 203 on the left side of the figure, each cable containing eight fibers (not shown). More particularly, the cables 201 and 203 terminate to suitable optical connectors 207 and 209, respectively, which engage with mating connectors 211, 213, respectively, through adapters 215, 217 disposed in the housing 102. For each of the eight right-hand cables 201, the fibers 105 embedded in the shuffle 100 break out the eight signal paths and distribute one each to each of the eight left-hand cables 203, and vice versa.
Flexible optical circuits such as shuffle 100 of FIGS. 1 and 2 can be bent too sharply. Particularly, there are three concerns with respect to bending flexible optical circuits too sharply. First, the optical fibers 105 embedded within them can break if bent too sharply. Secondly, even if the fibers do not break, too sharp of a bend in a fiber can cause light to escape from the core of the fiber, thus leading to signal loss. Finally, the flexible optical circuit substrate usually is a laminate, and bending a laminate too sharply can cause it to de-laminate.